DESCRIPTION: The first aim of this application is to determine if perceptual responses to odors can be influenced by labels provided by the experimenter or by a subject's implicit beliefs about the health benefits or hazards of the stimulus. In Experiment 1, subjects will rate the intensity of a suprathreshold concentration of an ambient odorant and clean air. Pre and -1-A second aim of the project will be to determine the ability of attention or arousal to influence the perceptual responses to odors previously classified as "hazardous." Experiment 3 will use the psychophysical tests described in Experiment 1 except that subjects will be given a task that either has high or low demands on attention during the odor exposure period. High demand subjects will rate intensity every minute whereas low demand subjects will rate the intensity only at the beginning and end of the exposure period. In Experiment 4, the subjects will be presented with continuous 85 dB white noise (high arousal) or 60 dB white noise (non-arousal) delivered through headphones during the odor exposure period.